1. Field of the Invention
The present invention relates to the field of linear motors which include a coil surrounding a magnet assembly.
2. Description of the Prior Art
U.S. Pat. No. 5,345,206 issued to Anthony C. Morcos on Sep. 6, 1994 and assigned to BEI Electronics, Inc. discloses a cylindrically-symmetrical moving coil linear actuator.
The actuator utilizes axially-magnetized cylindrical magnets to provide flux-focused interleaved magnetic circuits. The actuator includes a cylindrical shell that has a closed end and an open end. A magnetic core is disposed within the shell to define an annular air gap between the shell and the core. The core includes a first set of axially-magnetized cylindrical permanent magnets having a first direction of magnetization and disposed adjacent the closed end of the shell. A second set of permanent magnets has a second direction of magnetization which is opposite to the first direction of magnetization and is disposed adjacent the open end of the shell.
A moving coil assembly is disposed with the annular air gap. The coil assembly includes a non-magnetic coil carrier. A first coil winding is formed on the coil carrier in proximity to a first set of magnets and is wound to have a first polarity. A second coil winding is formed on the coil carrier in proximity to a second set of magnets and is wound to have a second polarity opposite to the first polarity such that the first and second coil windings are wound in opposite directions.
The invention disclosed in U.S. Pat. No. 5,345,206 can be improved upon. Specifically, the use of two coils increases the gap requirement between the magnet assembly and the housing, thereby reducing the force output of the linear motor. There is a significant need to improve the force output with this design.